The present invention generally relates to digital video signal reproducing apparatuses, and more particularly to a reproducing apparatus for reproducing a digital video signal which is related to a plurality of pictures and is time-sequentially recorded on a recording medium.
Generally, there is a known reproducing apparatus which reproduces a digital video signal recorded on tracks formed on a rotary recording medium (hereinafter simply referred to as a disc) as variations in rows of intermittent pits. The digital video signal is obtained by subjecting a video signal to a digital pulse modulation such as a pulse code modulation (PCM). As systems for reproducing the recorded digital video signal from such a disc, there is a system which reproduces the recorded signal in response to variations in the intensity of light reflected from or transmitted through the disc according to the variations in the pits formed on the disc, and a system which reproduces the recorded signal in response to variations in the electrostatic capacitance formed between a reproducing stylus and the disc according to the variations in the pits formed on the disc.
If the conventional digital video signal reproducing apparatus of the above type is a reproducing apparatus for time-sequentially transmitting a plurality of still picture information recorded on the disc, two frame memories are provided in the reproducing apparatus, for example. In such a reproducing apparatus, still picture information related to one or less frames is alternately written into these two frame memories. When one of the frame memories is writing therein a reproduced digital video signal, a reproduced digital video signal is read out from the other frame memory. The signal read out from the frame memory is successively passed through a digital-to-analog converter and an encoder, and then supplied to a television receiver which reproduces the signal as a picture.
The above digital video signal reproducing apparatus further comprises a synchronizing signal generator (SSG) which generates a write-in clock signal and a read-out clock signal for the memory, a horizontal synchronizing signal and a vertical synchronizing signal of a reproduced video signal which is in conformance with a standard television system and is produced from the encoder, and other various signals required upon reproduction. The disc is rotated in phase with the horizontal synchronizing signal obtained from this SSG. Among the plurality of still picture information time-sequentially recorded on the disc, a picture switching code for switching the memory from which the read-out is to be carried out from one of the two memories to the other, is recorded between adjacent still prcture information.
However, the digital video signal and the picture switching code which are reproduced from the disc, are not in phase with the vertical synchronizing signal obtained from the SSG. Thus, it was possible for the switching point of the picture to appear within the reproduced picture. Accordingly, the quality of the reproduced picture became deteriorated when switching the display of the reproduced picture from one picture to another in the conventional digital video signal reproducing apparatus. In addition, there was a problem in that the brightness appeared to be different in the top and bottom of the reproduced picture according to the pattern of the picture.